膜层厚度对金属薄膜光学常数的影响

从麦克斯韦方程出发,可以得到超薄金属膜层光学常数n、k与其厚度有关系的理论依据。采用电阻热蒸发和电子束热蒸发的方法在K9玻璃基底上分别沉积了不同厚度的Cu膜、Cr膜、Ag膜,由椭偏法检测、Drude模型拟合,获得了不同厚度Cu膜、Cr膜、Ag膜光学常数n、k随波长λ的变化规律。超薄金属薄膜与块状金属的光学常数相差较大,随着薄膜厚度的增加,n、k值趋近于块状金属。通过对样品膜层吸收、色散特性的分析,发现连续金属薄膜在可见光波段对长波的吸收较大,而且相比于介质薄膜平均色散率高10mn～102nm量级。     

基于激光外差干涉术的薄膜厚度测量方法

针对光学薄膜厚度测量困难问题，提出了一种基于激光外差干涉术的薄膜厚度测量方法。采用经典迈克尔逊干涉光路，利用外差干涉原理将薄膜厚度差转换为光程差，以精密位移平台为扫描机构实现薄膜厚度的逐行扫描测量。测量系统在恒温实验条件下20 min内的漂移不超过8 nm，测量结果平均差小于1 nm，通过与椭圆偏振仪的测量结果比较，测量差值为12.97 nm，表明了该方法的可行性。     

Optical diagnostics of nanoscale dielectric layers on interference films by polarization-dependent differential reflectivity

The small change in the reflectance (differential reflectance) of s- or p-polarized light from an interference film as a result of the deposition of a nanoscale insulating layer on it is investigated theoretically. Analytical relations describing the contribution of nanoscale layers to the reflectance from an interference film as function of film thickness are obtained in the long-wavelength approximation. It is shown that the utilization of interference films in reflection diagnostics through differential measurements allows a significant enhancement of the sensitivity of these techniques and also opens up new possibilities for resolving the inverse problem of determining simultaneously the optical constant and thickness of nanoscale dielectric layers.     

Effect of Boundary Conditions on the Electrical and Galvanomagnetic Properties of a Thin Metal Film

The problem of determining the high-frequency electrical conductivity and Hall constant for a thin metal film placed in a transverse stationary magnetic field and in a longitudinal alternating electric field is solved by the kinetic method. The relation between the film thickness and electron free path length is supposed to be arbitrary. The skin effect is not taken into account. The diffuse-specular mechanism of electron reflection from the film boundaries is considered with similar specular-reflection coefficients for the upper and lower surfaces of the film taken into account. The electrical conductivity and Hall constant are studied as functions of dimensionless parameters: electric-field frequency, magnetic-field induction, and film thickness.     

A method for measuring the complex refractive index and thickness of a thin metal film

A circularly polarized heterodyne light beam is incident on a thin metal film, causing successive reflections and refractions to occur at the two sides of the thin film. The phase difference between p- and s-polarizations of the multiple-beam interference signal can be measured accurately with an analyzer and heterodyne interferometry. The phase difference depends on the azimuth angle of the analyzer, the complex refractive index and the thickness of the thin metal film. The measured values of the phase differences under three different azimuth angles of the analyzer can be substituted into the special equations derived from Fresnels equations and multiple-beam interference. Hence, the complex refractive index and the thickness of the thin metal film can be estimated by using a personal computer with a numerical analysis technique. Because of its common-path optical configuration and its heterodyne interferometric phase measurement, this method has many merits, such as high stability against surrounding vibrations, high resolution and easy operation. PACS 78.66.Bz; 78.20.Ci; 07.60.Cy     

Behaviour of transmittance and phase change on transmission with film thickness at intermediate thicknesses

The behaviour of the optical functions T (transmittance) and X_t (phase change on transmission) for an absorbing film have been investigated as the film thickness was increased from a small fraction of a wavelength up to a thick solid. When plotted against thickness, the values of T oscillated at a frequency related to the quantity, x=2πd/λ which is equal to the phase thickness divided by the refractive index. Ultimately, for real materials, the oscillations were damped to zero due to the absorption term in the complex dielectric constant of the film material. In the case of X_t, the most notable feature was the sudden phase changes of ±π which occurred repeatedly as the thickness increased and the values of x at which this occurred could be related to the conditions for constructive or destructive interference between light rays coming from the top and bottom of the film.     

基于透射谱的GaN薄膜厚度测量

通过对蓝宝石衬底异质外延GaN薄膜光学透射谱的分析，结合晶体薄膜的干涉效应原理并考虑折射率随光子波长变化的影响，从理论上推导出了实用的薄膜厚度计算方法. 实际应用表明，该方法是一种快速准确的GaN薄膜厚度测量方法. 关键词： GaN 透射谱 厚度测量     

THz波段介质涂敷空芯金属圆波导的传输特性

针对THz波段介质涂敷空芯金属圆波导传输特性的精确分析问题,基于波导中场方程及边界条件建立关于传播常数的特征方程,并且采用改进的Muller法求解特征方程得到涂敷圆波导主模HE11模的传播常数。计算中对THz波段的非理想导体电导率采用经典弛豫效应模型。仿真结果表明:内径为1.8 mm的银波导,当聚苯乙烯涂敷层厚度为17 m时,HE11模在1.5~3.0 THz的衰减常数在1 dB/m以下,且具有较好的色散特性;内径为2.2 mm的银波导,在2.5 THz时其衰减常数随涂敷层厚度的增加先增大后减小,且存在最佳介质涂敷层厚度,可实现THz波低损耗传输。     

反射干涉光谱法测量固体薄膜的光学常数和厚度

本文报道一种简单的方法,从平原介质薄膜的反射干涉光谱来计算薄膜的光学常数和厚度。当一束光照射在基板上的介质膜上时,由于膜上下界面反射光的相干,会使反射光谱的曲线有一定的波动。我们对反射相干光谱进行理论分析,给出计算公式,从测量曲线中的实验值得出薄膜的光学常数ｎ、ｋ以及厚度等参数。此种方法简单可行,而且易于编程处理。     

超二代微光像增强器多碱光电阴极膜厚测量研究

介绍了多碱光电阴极的光学性能和光谱反射率特性,测量了多碱阴极的光谱反射率曲线.该曲线与普通光学膜层光谱反射率曲线相比,形状较不规则,原因是多碱阴极膜层存在光吸收.光谱反射率曲线上的干涉峰是入射光在玻璃与阴极膜层界面反射和在阴极膜层与真空的界面反射的两束光发生干涉的结果.根据干涉的原理,如果阴极膜层所反射的两束光的光程差为二分之一波长的偶倍数时,光谱反射将出现干涉加强峰;如果阴极膜层所反射的两束光的光程差为二分之一波长的奇倍数时,光谱反射将出现干涉减弱峰.根据超二代像增强器光谱反射干涉峰对应的波长,可以计算出其阴极膜层的厚度约为191 nm,比二代像增强器阴极膜层的厚度增加了38％.多碱阴极膜层厚度是影响多碱阴极灵敏度的一个关键参量,仅仅靠人眼观察阴极膜层颜色的方法不准确.实践证明,利用光谱反射的方法来计算阴极膜层厚度的方法简单有效.如果在多碱阴极的制作过程中进行光谱反射率的监控,那么将可以精确控制阴极膜层的厚度,对多碱阴极的研究将会更加深入,多碱阴极的灵敏度也将会得到进一步的提升.     

基于GIXRR反射率曲线的二氧化硅纳米薄膜厚度计算

为了快速、准确得到纳米薄膜厚度,采用Kiessig厚度干涉条纹计算薄膜厚度的线性拟合公式,计算了不同系列厚度(10~120 nm)的二氧化硅薄膜。薄膜样品采用热原子层沉积法(T-ALD)制备,薄膜厚度使用掠入射X射线反射(GIXRR)技术表征,基于GIXRR得到的反射率曲线系统讨论了线性拟合公式计算薄膜厚度的步骤及影响因素,同时使用XRR专业处理软件GlobalFit2.0比较了两种方法得到的膜厚,最后提出一种计算薄膜厚度的新方法-经验曲线法。结果表明：峰位级数对线性拟合厚度产生主要影响,峰位级数增加,厚度增大;峰位对应反射角同样对线性拟合厚度有较大影响,表现为干涉条纹周期增大,厚度减小。但峰位级数及其对应反射角在拟合薄膜厚度过程中引入的误差可进一步通过试差法,临界角与干涉条纹周期的校准来减小。对任意厚度的同一样品,线性拟合和软件拟合两种方法得到的薄膜厚度具有一致性,厚度偏差均小于0.1 nm,表明线性拟合方法的准确性。在厚度准确定值的基础上提出薄膜厚度与干涉条纹周期的经验关系曲线,通过该曲线,可直接使用干涉条纹周期计算薄膜厚度,此方法不仅省略了线性拟合过程中确定峰位级数及其对应反射角的繁琐步骤,而且避免了软件拟合过程中复杂模型的建立,对快速、准确获得薄膜厚度信息具有重要的意义。     

周期或准周期超晶格薄膜表面吸附原子的自发辐射性质

本文把由库理论和耗散系统量子化方法所求得的表面修饰的光学布洛赫方程,同麦克斯韦方程自洽地相结合,求得周期或准周期超晶格薄膜表面吸附原子的自发辐射寿命和频移,讨论了构成该薄膜各层的厚度和介电性质及总层数对上述自发辐射性质的影响。同时,把周期性情况和准周期情况分别求得的结果进行了比较。 关键词：     

Calculation of the RF Conductivity and Hall Constant of a Thin Metal Film

The kinetic problem of finding the rf conductivity and Hall constant of a thin metal film placed in a transverse steady magnetic field and a longitudinal variable electric field has been considered. It has been assumed that electrons diffusely reflect from the upper and lower surfaces of the film. No limitations have been imposed on the relationship between the thickness of the film and the electron free path. The dependences of the conductivity and Hall constant on dimensionless parameters, namely, electric field frequency, magnetic field induction, and thickness of the film, have been studied. Calculation results have been compared with the experimental data.     

Regularities in penetration of electromagnetic waves through metallic magnetic films

Penetration of millimeter electromagnetic waves through permalloy films under magnetic resonance conditions is studied experimentally and theoretically. Measurements are taken on film samples from 40 to 200 nm in thickness in a frequency range from 26 to 38 GHz. Magnetic resonance, antiresonance, and spin-wave resonance are observed. The resonance spectrum is reconstructed. The Gilbert damping constant is determined for a series of films. It is shown that the damping constant decreases upon an increase in the film thickness. The resonance line profile is calculated, and the dependences of resonance line amplitude and width on experimental conditions and material parameters of the film are determined.     

基于等色干涉的膜分析

基于膜等色干涉原理,将等色干涉条纹与已知线光谱在光谱仪谱面上叠加,通过对干涉条纹宽度及其变化的测量,可计算出膜厚、膜厚突变、膜厚渐变等.对膜进行扫描分析,膜的面积达10-2mm2数量级即可进行测量.     

各向异性聚合物薄膜参数的测量与计算

讨论了用单侧漏模法测量薄膜共振漏模的耦合角、计算漏模的有效折射率并由相应的模方程来确定各向异性聚合物薄膜折射率ｎ０、ｎｅ及厚度ｄ的方法。对ＰＴ－ＰＥＫ－ｃ（酞酸铅－聚醚醚酮）膜，测量与计算结果为：ｎｏ＝１．６５２５±０．００１４，ｎｅ＝１．６４３９±０．００１９，ｄ＝２．３３±０．３２μｍ。     

Crystallization and annealing effects of sputtered tin alloy films on electromagnetic interference shielding

Sn, Al and Cu not only possess electromagnetic interference (EMI) shield efficiency, but also have acceptable costs. In this study, sputtered Sn-Al thin films and Sn-Cu thin films were used to investigate the effect of the crystallization mechanism and film thickness on the electromagnetic interference (EMI) characteristics. The results show that Sn-xAl film increased the electromagnetic interference (EMI) shielding after annealing. For as-sputtered Sn-xCu films with higher Cu atomic concentration, the low frequency EMI shielding could not be improved. After annealing, the Sn-Cu thin film with lower Cu content possessed excellent EMI shielding at lower frequencies, but had an inverse tendency at higher frequencies. For both the Sn-xAl and Sn-xCu thin films after crystallization treatment, the sputtered films had higher electrical conductivity, however the EMI shielding was not enhanced significantly.     

Magnetization reversal processes in FeSm thin films

We have investigated the in-plane magnetization reversal in FeSm thin films and discovered that it can be controlled through an induced anisotropy. For films with an induced easy direction, reversal is ultra fast and can be characterized approximately using the Fatuzzo model. In films with no pronounced induced easy axis, the reversal is much slower and can be described using a logarithmic model. We have also investigated the short time (1–50 s) dependence of the remanent coercivity and fitted to logarithmic equations. For films with no pronounced easy axis, the time dependence of the coercivity correlates with the film thickness, indicating that the switching volume scales with thickness. For films with an induced easy direction, the time dependence of the coercivity is essentially constant, independent of film thickness, indicating no scalable switching volume.     

应力对La0.83Sr0.17MnO3薄膜输运性能的影响

采用溶胶-凝胶方法在Si(111)上制备了LSMO(x=0.17)薄膜.研究了块体材料和不同厚度薄膜R -T曲线、红外光谱和X射线衍射.结果表明，LSMO薄膜属于正交晶体结构，薄膜取向与膜厚度 有关，当膜厚度为450nm或680nm时，主要取向〈200〉，而膜厚度为900nm时取向为〈020〉 ：根据离子对相互作用能和谐振子模型，得到了红外吸收与Mn—O—Mn键长和键角关系式，6 00cm^-1附近红外吸收与晶格常数b的变化有关；块体与薄膜的金属—绝缘体转变 温度(T_MI)存在较大差别，薄膜转变温度显著低于块体，并与厚度有一定关系. 认为是LSMO薄膜中的应力诱导了晶格常数变化，引起键角改变及JT效应是转变温度变化的主 要原因. 关键词： 单晶硅 晶格常数 金属—绝缘体转变温度 应力诱导     

Luminescence and resonance fluorescence of an adatom near a surface of a superlattice film periodic of quasi-periodic structure

The surface-dressed optical Bloch equations derived from the reservoir theory and Dekker's quantization procedure and the Maxwell equations are used to obtain the spontaneous decay time and frequency shift, the resonance fluorescence spectrum, and squeezing effects of an adatom adsorbed near a surface of a periodic or quasi-periodic superlattice film. The effects of the thickness and dielectric properties of the layers in the film, number of layers, and different geometry structures are discussed, and the results for the two different cases of periodic structure and the quasi-periodic one are compared.